Yes, twice this year.
Route: fly over the islands; theoretically you could get across in one hop but you wouldnt have any fuel for a diversion to an alternate. We carried extra fuel enabling us to continue from NZ to Norfolk and then onwards to La Tontuta, New Caledonia (has ILS)
Customs: if you are not importing/exporting its quite easy. Just a crew declaration, cash declaration if you carry cash and your entry/departure cards. Have it all sorted before departure and everyone will be happier along the route. If you are importing -get a GOOD customs broker. You must enter and leave the country from a customs airport so we used KeriKeri. Kaitaia is closer but KK is close to Opua which is a favoured entry point for pleasure yachts and so there is a guy living up there. Will cost you a couple of hundred nz to get him out on sundays. You need to notify customs at latest 24hrs to international ops. Form om nz customs website.
Customs are easy but the DAF (the pest people) are fairly anal and so you must enter the country at a place where there is not only customs but also DAF. They will require you to spray the aircraft before exiting or opening doors. No big deal and no you wont die. If you did want to make life easier, get a bottle of the "top of descent" spray. Spray airborne and show can on arrival. (The Aussies will take it off you thou but the islands will let you keep it. )
Islands: Norfolk, friendly people but not an overly exciting place. Lots of pine trees. Elevation of apt is fairly high and wx changing rapidly so beware of the cloud. You may not be able to and on into wind rwy as the threshold may be too high. (As was the case when I flew in once) When fire service are on stby they score the landings of incoming Jets and write it on a big board outside their station for when you taxi past. -lol
Lord Howe; tropical paradise. Lots of cool mountains and theres Balls Pyramid which is a strange very tall rock formation poking out of the sea some 10nm south of LHI. Check it out!
LHI gets EXTREMELY bad turbulence (qantas q300 cant get in) with wind from certain angles and over 12kt strengths (which is most of the time). Wind direction can be very different each end of rwy so a second met station is positioned on the western threshold which will broadcast in different voice on AWIB.
Recommend stay a night or two at the pine tree place (appears expensive but all meals included and its great -they even packed a lunch bag for us!) Locals throw great parties.
The Island people are very helpful and will phone each other to ensure your safe arrival. Make sure however you call ahead to all the places.
FUEL; in NZ, BP and Z have bowsers everywhere but credit card always works, however for credit card you must call ahead. In fact, always call ahead just to be sure. NF gets its AVGAS in drums but put it into a underground tank.
Procedures; IFR -must have HF, VFR; pretty sure you don't but not 100%.
Have a liferaft and if single, I would grab an immersion suit. Consider a Personal Locator Beacon, cheap but can be hired also. We use them all the time for offshore yacht racing.
Norfolk is Aussie territory but halfway from LHI you will enter Auckland FIR. Oceanic, go flightlevels -set 1013 and when in NZ hemispherical is north/south, not east west. Rule of thumb: they are Odd in Auckland (north odd).
We flew at 55% all way to conserve fuel but it made for a long haul, despite being in a twin. I found the fuel numbers in the manual to be extremely accurate. If you have retractable gear, also consider PNR for a gear malfunction causing the gear to fall out half way (loss of hydraulic pressure)
Pee bottles could be good just in case. We carried but did not use as our flight times wee only 4.5hrs however with the ferry tank we had 11hrs endurance or there abouts.
International flight plan, very similar to normal but you also give an email address to which a copy will be sent.
Make sure your nav equipment is certified for sole means oceanic - between NF and NZ there is 100nm out of range between KT and NF NDB. Also, grab an iPad. You need ERC H5 to get across the ditch and from there, the NZ charts.
Thats about all I can think of for now.
/mr.ferrypilot